1. The Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, embodiments of the invention relate to expandable medical devices, such as introducer sheaths, for use during medical procedures.
2. The Relevant Technology
A wide variety of devices have been developed for medical use. One such device is an introducer sheath that facilitates access to body lumen at an access site. Conventionally, introducer sheaths are formed of three or more components that require assembly: a sheath portion, a hub, and a hemostasis valve disposed within the hub. A suitable example of such an assembly is shown in U.S. Pat. No. 5,807,350, which depicts an introducer sheath having a construction similar to that described above, the entirety of which is hereby incorporated by reference.
In practice, introducer sheaths are often used to access a vessel or artery to allow a surgical or medical procedure to be performed. The introducer sheath is generally inserted into a patient's vasculature using the modified Seldinger technique. In the Seldinger technique, a needle is first inserted into the vessel and then followed by a guidewire through the needle. Next, the needle is removed and a sheath/dilator combination is advanced over the guidewire. The sheath/dilator expands the puncture in the vessel to a size suitable to receive the distal end of an introducer sheath. After the distal end of the sheath is disposed within the vessel, the dilator and guidewire are removed, thereby allowing access to the vessel lumen through the introducer sheath.
There are an increasing number of medical procedures that can be performed using sheaths. Medical procedures such as angioplasty, stenting, and intraaortic therapy, are examples of procedures that can include the use of introducer sheaths. In particular, the medical devices (e.g., catheters, balloon pumps) used in these procedures are introduced through the sheath.
Some of these procedures unfortunately require removal of the sheath earlier than desired. For example, intraaortic balloon pump therapy for ventricular insufficiency is often performed using a sheath. In this procedure, a sheath may be inserted into the femoral artery. Next, a balloon pump may be introduced into the patient's vasculature through the sheath and then guided to the aortic arch region. Once the balloon pump is properly positioned in the arch region, it is typically left in place until the ventricular insufficiency is improved to an acceptable level, which may take days.
In this procedure, the balloon pump may be inflated and deflated at a rate that typically matches the heart rate. Thus, the balloon pump is usually inflated during ventricular diastole and deflated during ventricular systole. Because of the use of the balloon pump for the intraaortic therapy, the balloon pump may be larger compared to when it was initially inserted through the sheath. Because of the increased size, removal of the balloon pump also requires the removal of the sheath since the enlarged balloon pump typically cannot fit inside of the sheath tubing. One of the disadvantages of removing the sheath along with the balloon pump is that the opportunity to close the vessel with any vessel closure device through the sheath may be lost.
Furthermore, the user typically removes the guidewire from the patient's body lumen in order to deploy the closure element. However, many users may wish to have guidewire access in case the need arises to re-access the site or if other complications arise upon closing. Thus, it may be desirable to deploy a guidewire into the body lumen in such a way that it does not interfere with the introduction of the closure element.
There is therefore a need for a new introducer sheath to accommodate removal and/or insertion of devices that change in size or that do not work with conventional sheaths. It may also be desirable to provide guidewire access in such a way that a closure element may also be introduced.